Interaction between buttons

[jipan@gmuvax2.gmu.edu (Jiqian Pan)]

I has been designing some code for timing with two buttons go and stop.
Once you click the button go, timing will start; once you click the
button stop, timing should stop.  However, the button stop did not
work while timing is going.  Does anyone fix my problems?  Thanks.

(setq foo (make-instance 'window
        :window-type :document-with-zoom
        :view-position '(:Top 150)
        :window-title "FLUENT-II"
        :view-size #@(400 300)
        :view-nick-name 'button-dialog
        :view-subviews
           (list
             (make-dialog-item 'button-dialog-item
                  #@(300 250)
                  #@(30 15) "go"
                   #'(lambda (item) item (clock-my))
                  :view-font '("Times" 12 :SRCCOPY :bold ))
             (make-dialog-item 'button-dialog-item
                  #@(350 250)
                  #@(30 15) "stop"
                   #'(lambda (item) item (setq timing "false"))
                  :view-font '("Times" 14 :SRCCOPY :bold )))))

(defun clock-my() 
     (setq timing "true")
     (setq x-pos 250) (setq y-pos 100)
     ( dotimes (i 32)
      (move-to foo (make-point 250 150))
      (line-to foo (make-point x-pos y-pos))(delay-1)
      (if (equal timing "false")(return))
      (set-pen-pattern foo *white-pattern*)(move-to foo (make-point 250 150))
      (line-to foo (make-point x-pos y-pos))
     (cond ((<= i 15)
      (setq x-pos (+ 250 (round (* (sin (* PI (/ (* 12 i) 180))) 50))))
      (setq y-pos (- 150 (round (* (cos (* PI (/ (* 12 i) 180))) 50)))))
      (t (setq x-pos (- 250 (round (* (sin (* PI (/ (* 12 (- i 15)) 180))) 50))))
         (setq y-pos (+ 150 (round (* (cos (* PI (/ (* 12 (- i 15)) 180))) 50))))))
     (set-pen-pattern foo *black-pattern*)
      ))

(defun delay-1 ()
   (dotimes (i 123456)
      (* 123456789 987654321)))

jipan@gmuvax2.gmu.edu